Epoxy resins have heretofore been advanced in the presence of phosphonium catalysts disclosed by Dante in U.S. Pat. No. 3,477,990 and Perry in Canadian Pat. No. 893,191 and U.S. Pat. No. 3,948,855. However, the quantities of catalyst employed were that which would provide a resin having a percent epoxide value sufficiently close to the theoretical epoxide value that no improvement in properties were envisioned.
An allowed application Ser. No. 212,959 filed Dec. 4, 1980, now U.S. Pat. No. 4,352,918 by Whiteside, Gist and Doorakian, disclosed the preparation of advanced epoxy resins having improved physical properties by employing a sufficient quantity of a phosphonium catalyst such that the resultant advanced epoxy resin has a percent epoxide value lower than the theoretical percent epoxide value.
The process of the present invention provides a method for preparing advanced epoxy resins having a percent epoxide value lower than the theoretical percent epoxide and a desirably lower color than the color provided by those advanced epoxy resins produced by the process described in the aforementioned allowed application Ser. No. 212,959.